The following publications are believed to represent the current state of the art:
U.S. Pat. Nos. 7,843,339; 7,170,409; 6,874,092; 6,853,093; 6,646,565; 6,438,825; 6,414,884; 6,359,338; 5,998,858; 5,877,547; 5,861,662; 5,675,319; 5,353,350; 5,237,307; 4,807,284 and 4,593,384;
U.S. Published Patent Application No. 2005/0184870;
European Patent Nos. EP0375545 and EP1432031;
Great Britain Patent No. GB2372363A;
Van Ess, Dave; “Capacitive Touch Switches for Automotive Applications,” http://www.automotivedesignline.com, February 2006; and
Kremlin, Victor, et al., “Capacitive Sensing—Waterproof Capacitance Sensing”, Cypress Perform, December, 2006.